6. Abstract Each year smoking kills 430,000 U.S citizens, exacerbates a myriad of diseases, and costs society approximately $100 billion. Despite the proliferation of information and restrictive smoking policies, adult smoking prevalence has remained relatively stable during the past five years, currently at 21%. Brief physician- delivered tobacco treatment, commonly known as the 5As, is an evidence-based intervention demonstrated to double a smoker's likelihood of quitting. Given that 70% of smokers see a physician each year, it is imperative that all clinicians have the appropriate knowledge and skill level to counsel smokers. However, few physicians and physicians-in-training receive adequate training to develop these skills. Using a pair-matched, randomized group-controlled (RGC) design (implemented in 10 medical schools), we will compare two methods of teaching the 5As to medical students: 1) traditional medical education (TE), and 2) multi-modal education (MME) that adds two components to TE: a web-based instructional program for students and preceptor training. The primary outcome is observed tobacco treatment counseling skill as measured by the Objective Structured Clinical Examination (OSCE), the standard method for evaluating medical student skill level at all U.S. medical schools. A secondary outcome is self-reported tobacco treatment counseling skill level. In a nested cohort design, during the second year of the study a cohort of medical students will be followed from early in their first year of medical school (MS1) through the end of their third year (MS3) which occurs in the 4th year of the study. The Primary Aim of this RGC trial is to compare the effectiveness of MME for teaching the 5As counseling skills in medical school against TE. Hypothesis 1: MME will outperform TE on observed 5As counseling skills (OSCE). Hypothesis 2: MME will outperform TE on self-reported 5As counseling skills. Strengths of this study include: 1) the innovative study design that tests common and integrative teaching methods and 2) the potential to disseminate throughout US medical schools effective educational methods that can build physicians' skills to assist the millions of patients who continue to smoke. This is a unique window of opportunity to build on our team's prior research in medical education and tobacco dependence treatment. This study involves close collaboration among researchers, practitioners, educators, and stakeholders at 10 U.S. medical schools. This unique team is comprised of investigators with extensive experience developing and teaching an evidence-based, physician-delivered 5A tobacco treatment model; developing and evaluating a web-based tobacco dependence treatment course; implementation of academic detailing with physician preceptors; and experience in building a large medical school consortium for tobacco curriculum reform.